Monday, December 29, 2008

Preparation of SEMCl

SEMCl (2-trimethylsilylethyoxymethyl chloride)
expensive, 25ml $500
so just make it!

st: 2-TMS ethanol 1.o eq. (100 g, $500)
paraformaldehyde 1.1eq.
control temperature below 20C by ice bath.
Bubble HCl gas through the mixture. exothermic. HCl flow rate need to be controlled so that the INSIDE temp below 20C.
after a while, about 10-20 min, the solution became two layers and both are clear. then stop HCl gas.
separate the top layer. dilute the top layer with pentane and dried it over mgso4 at 0 C for 1 hr.
then concentrated below rt.
what you have now is pure semcl! ready to use. H-NMR showed only pure compound.

stored over CaCl2 in freezer.

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